Wireless Local Area Networks (“WLANs”) generally include a plurality of access points in communication with a switch for providing wireless access to mobile client devices. Currently, WLANs are most often used to provide access to mobile devices such as laptop computers. Since most users do not walk around while using a laptop computer, no great need was felt for high-performance mobility to support roaming between access points. However, with the current trend toward developing WLANs that support mobile phones a need has arisen for improved mobility. Further, the security protocols and QoS controls that were generally acceptable for data communications are problematic for support of voice communications on WLANs
It is generally known in the art that Virtual Local Area Networks (“VLANs”) such as specified by the IEEE 802.1Q standard can be used to facilitate mobility, including support for voice communications over WLANs. VLANs differentiate traffic by pre-pending packets originating from devices in a particular VLAN with a tag that is indicative of the VLAN. In terms of support for voice traffic, voice clients can be differentiated from data clients by assigning voice clients to one or more distinct VLANs. Further, priority may be give to the VLAN that supports voice traffic, thereby providing some level of QoS control. Still further, traffic on the voice VLAN may all be directed through a particular gateway or other network device, thereby providing a level of security.
Typically, the VLAN tag for a particular packet is determined at a switch or server. In particular, the switch or server examines the packet and uses fields such as the source and destination MAC address to index into a table that yields the appropriate VLAN for the packet. However, determining which VLAN is associated with a packet can be computationally costly because the MAC address fields are relatively long, resulting in a large table. This can be problematic as the number of supported wireless clients increases.